U.S. Pat. No. 5,874,988 describes a system and a method for automatically correcting the colors in a film scanner. This patent describes how correction is performed by managing statistical parameters linked to a source image and by comparing these statistical parameters with those of a reference image, with the reference image data being memorized. The statistical parameters are the gain, the gamma-factor and the black level. Correction is performed until the adjustment is optimized between the reference image parameters and the statistically determined parameters of the objective to be achieved for the source image. This patent, for adjusting film scanner colors, is based on the statistical analysis of the pixels between two images, one source image and one reference image; it does not take into account sensitometric measurements made on the film strip to be digitized.
U.S. Pat. No. 6,115,062 describes a system and a method for calibrating a film scanner using a reference film strip with known optical densities. The gain, gamma and black level are adjusted in relation to this calibrated reference strip with preset optical density levels and corresponding to three different gray levels. For the film scanner to be correctly adjusted, the video signal or output voltage must match the optical densities of the three preset gray levels. This patent does not take into account sensitometric measurements made on the film strip to be digitized.
It is especially useful to optimize the calibration methods of digitizing equipment, in particular in the field of the motion picture industry. The objectives of quality and cost, and thus of productivity linked to this industry involve using reliable and fast digitizing equipment, capable of adapting to all types of film to be digitized.